Method and apparatus for making dry ice



April 1939- J. KOBOLD 2,153,629

METHOD AND APPARATUS FOR MAKING DRY ICE Filed Dec. 24, 1937 2 Sheets-Sheefl Fig. 2

Fig. 7

April 1939. I J. KOBOLD 2,153,629

METHOD AND APPARATUSFOR MAKING DRY ICE File'd Dec. 24, 1937 2 Sheets-Sheet 2 Patented Apr. 11, 1939 METHOD AND AIPARATUS FOR MAKING DRY ICE Josef Kobold, Esslingen-on-the-Neckar, Germany, amignor to Maschineniabrik Esslingen, Esslingen-on-the-Neckar, Germany, a. corporation of Germany Application December 24, 1937, Serial No. 181,522

9 Claims.

For this purpose the snow production and there-' with the limitation of the size of the block are regulated by time. Beside other conditions the size of each block is therefore particularly-dependent upon the attentiveness of the operator and is consequently often very irregular.

In order to provide an uninterrupted operation, at least two such producers are used,

each

being equipped with a hydraulic press cylinder for snow compression and preferably also in most cases with hydraulic means for the operation of the cover plates for the compressing cylinders.

The hydraulic press cylinders are operated a press pump unit. ,Such devices are bulky and expensive and complicated in operation.

The invention described hereinafter by ence to illustrative embodiments thereof tutes an important advance both in respect from referonstito the quantity ofliquid carbon dioxide for each block -of dry ice, before expansion of the same in the snow production cylinder. In this way, blocks of dry ice of uniform weight are produced. At the same time, the measuring cylinder serves also as an actuating cylinder for the dry ice press, the,

liquid carbon dioxide under condenser pressure acting as a pressure fluid.

The drawings show diagrammatically s illustrative forms of the invention.

everal Fig. 1 is a diagrammatic view of a dry ice producing unit in operation, including a longitudinal section of the snow compressing chambers their operating means;

Fig. 2 is a sectional view of the compr and essing at the end of an operation;

Fig. 3 is a diagrammatic view of a som ewhat simpler dry ice unit for smaller outputs, showing a compressing cylinder and hy'dfaulic for in section; and

Fig. 4 is a sectional view of the compr press thereessmg Germany January 9, 1937 chamber and hydraulic press shown in Fig. 3, with a slight modification, the parts being in a different position corresponding to the end of an operation.

0n the same horizontal axis stand the two compressing cylinders i and 2 for carbon dioxide snow, between them the hydraulic press cylinder 3, and at the ends, the hydraulic press cylinders I and 5 for operating the cover plates 6 and l. The latter are provided with counter pistons 8 and 9, respectively. Piston III in hydraulic press cylinder 3 is rigidly connected with the plungers II and i2 of the carbon dioxide'snow compressors by a common piston rod I3.- The plungers ii and i2 have some play within the inner cylinder walls and are furthermore provided with many small holes to establish communication between the two sides of the cylinder. The piston Ill fits tightly in the cylinder 3. The liquid carbon dioxide flows out of condenser l4 into a small collector drum i5, from which it is conveyed by a pipe l6 through heat exchanger ll, thence either through valve I8 to the side 3a of the press cylinder, or through valve i9 to the side 3b of the press cylinder. The side 3a is connected through valve and pipe 2| to injection nozzle 22 in the side 2a of cylinder 2. The side 3b of cylinder 3 is connected through valve 23 and pipe 24 with a nozzle 25 in the side ia .of cylinder i. Also; a-

pipe 26 provided with a valve 21 leads from the side ibof cylinder i to heat exchanger ll, whence a pipe 31 leads to the suction side of liquefying compressor 38. Likewise the side 21) of cylinder 2 is connected by a pipe 28 provided with a valve 29 with the heat exchanger and through pipe 31 with the liquefying compressor. The pressure side of compressor 38 is connected by pipe 39 with condenser M. The press cylinders i andZ for carbon dioxide snow can be either round or rectangular, the pistons being of conforming shape. Alternatively the round press cylinders i and 2 may receive rectangular inserts 30 (Fig. 2), which can be removed, so that by-suitable change of the pistons 3| and 32 round or rectangular dry ice blocks can be made.

The apparatus operates in the following manner:

When the valves i8, 23, and 21 are open and valves i9 and 20 closed, as in Fig. Land the cover plates 6 and 1 are in position and stand under pressure, liquid carbon dioxide flows from condenser through the small collector drum l5, through heat exchanger I1 and into the cylinder side So, while at the same time liquid carbon dioxide flows out of cylinder side 31) and is exwhile the unsolidified gases are sucked off by the liquefying compressor at a suitable place, for example, in the embodiment shown, laterally past plunger II and through the holes in the same, theme from cylinder side lb through valve 21, pipe 26, heat exchanger i1 and pipe 31. In the heat exchanger H the incoming liquid carbon dioxide is cooled by the cool excess gases, before it entersthe cylinder 3. Gradually the cylinder side 36 is emptied of carbon dioxide, while carbon dioxide snow is produced in la, while cylinderside 3a becomes filled up with supercooled liquid carbon, dioxide, which stands under condenser pressure. 'Since this-is considerably higher than the liquefying pressure of the supercooled carbon dioxide in the cylinder side 3b, which is closed off from the condenser, the piston in shifts slowly toward the side 3b and presses the liquid carbon dioxide in this side to injection nozzle 25, supplementing the expansion of this carbon dioxide by its own pressure. By the excess pressure of cylinder side 3a the carbon dioxide snow in cylin'der Zn. from the previous operation is pressed into a dry ice block, up to the point of equalization of pressure, that is, until the piston ill becomes stationary. The excess pressure on the side 3a increases automatically from the condenser with increasing resistance of the dry ice being formed in 2a, whereby the specific compression pressure of-plunger i2 upon the dry ice block is increased-in accordance with the natural relation of the piston surface ill to the plunger surface l2 (corresponding to the relation: Volume of the required quantity of liquid carbon dioxide to volume of the carbon dioxide snow produced therefrom for a dry ice block). When the piston i comes to rest the excess gas valve 29 is closed and after letting out the remaining gas from cylinder 2, for instance into a gasometer,

the cover plate 1 with its counter piston 9 isj somewhat drawn back, but the piston 9 is not entirely pulled out. Now the piston l0 and plunger |2 follow toward the right again until the pressure is equalized. In this way it is also possible, by means of the hydraulic press cylinder 5 acting upon counter piston 9, to give a subsequent compression to the dry ice block from the opposite side, in order to produce a high uniform specific weight through the entire block, even when the length of the block in relation to its pressed surface is long. Then immediately the cover plate.'| -is withdrawn. Now together with the continuation of formation of carbon dioxide snow in the cylinder side la the completed dry ice block is pushed out of 20, until piston l9 reaches the end of its stroke in the cylinder side 3b and thereby completely emptiesthe latter of liquid carbon dioxide. At this moment the production of carbon dioxide Show in cylinder side lb is ended and the apparatus has assumed the condition shown in Fig. 2. After removal of the dry ice block cylinder 2 is again closed by cover plate I and then valves 3, 23 and 21 are closed and valves I9, and 29 opened. Thereupon the production of carbon dioxide snow in cylinder 2a begins, from the liquid carbon dioxide in the cylinder side 3a, while the carbon dioxide snow in cylinder la. is pressed to dry ice. The abovedescribed operation now takes place in the opposite direction. The speed of motion of piston depends upon the cross section of thenozzle apertures, that is to say, upon the capacity of the liqueiying unit; in any case it is very slow.

Figs. 3 and 4 show another example of the invention for smaller outputs. A production and compressing cylinder 4.] for carbon dioxide snow is provided with a perforated plunger 42, which has lateral play within the cylinder wall. Cylinder 4| is closed gas-tight by cover plate 60. From the cylinder side MD a pipe 59 provided with a valve 56 leads through a heat exchanger 54 to the first stage of a liquefying compressor 5|. The nozzle 44 for the liquid carbon! dioxide is connected by a pipe 45 with the side; 43b of hydraulic press cylinder 43. The pipe 45 can be closed by a valve 46. 'Hydraulic presspiston 50 is rigidly connected with dry ice compressor plunger 42 by means of a piston rod 41. The cylinder side 4311 is connected through a valv ,[48 with the suction side of the high pressure stage of a multiple stage liquefying compressor 5| for {the fluid carbon dioxide, and through a valve 49 with the pressure side of the high pressure stageof this compressor. The liquid carbon dioxide is pumped by the compressor to a condenser 52 from which it passes through a small collecting drum 53, through heat exchanger 54, and a valve 55 to the side 43b of the cylinder 43, filling this side with supercooled carbon dioxide under condenser pressure, and causing the piston 50 to move downward. The valves 55, 58, and 56 are first open and the valves 49 and 46 closed. Upon the cylinder side 432), which stands under condenser pressure, there is a pressure which predominates over, that in the cylinder side 43a which stands under the suction pressure of the last pressure stage of the compressor 5| By this excess pressure the plunger 42 is moved downward and the carbon dioxide snow in the production chamber 4|a is compressed into a dry ice block, up to the ,point of equalization of pressure. Now valve 56 is closed. After letting off 'the pressure of the excess'gas -from the cylinder side 4|b into a gasometer, the cover plate 60 is opened, whereupon the dry ice block is finally pushed out, while cylinder side 43b is gradually filled with liquid carbon dioxide. This stage of the operation is illustrated in Fig. 4. The speed with which piston 5|] moves downward depends upon the cross section of the valves 55, 48 and 49. "Now, the cover plate6ll isagain closed, likewise valve 56, and valves 46 and 56 are opened. Valve 48 remains closed andvalve 49 open. Now, since the liquid carbon dioxide supercooled by passage through the heat exchanger 54 is shut off from the condenser by valve 55, the pressure drops according to the temperature to which the carbon dioxide has been supercooled; Now there appears upon the cylinder side 43a a pressure increasing in accordance with the filling of the condenser 52 and drum 53 with liquid carbon dioxide. This increasing pressure ,is produced by the gaseous carbon dioxide pumped from the highest pressure stage of the pump 5|. This excess of pressure gradually forces up the piston 59 and presses the liquid carbondioxide in the cylinder side 43b through valve 46 and pipe 45 to the expansion nozzle 44, whereby the cylinder side 4|a is gradually filled with carbon dioxide snow. Uncondensed gases are sucked oil at a pressure below the triple point by compressor 5| through valve56 and heat exchanger 54, to cool the liquid carbon dioxide before it flows into the quantity of carbon dioxide condensed to a liquid in the meantime) is gradually drawn ofi through valve 48 into the highest stage of thecompressor. Now the piston 50 again moves downward as the cylinder side 43b fills up with intensely cooled liquid carbon dioxide, at the same time compressing the carbon dioxide snow in cylinder a. In this way the process begins again.

Also with this apparatus round and quadrangular ice blocks can be produced, according to whether the round piston 42 of Fig. 3 is used, or the four-cornered piston 51 with the four-cornered insert 58 in the cylinder 4|.

In the manner outlined it is possible with the described apparatus to expand a quantity of liquid carbon dioxide exactly measured for each block of ice and corresponding to the volume of cylinder 3 or 43, thereby producing" blocks of uniform size, while using the liquid carbon dioxide under the condenser pressure asa pressure liquid. Cylinder 3 (l3) with piston I (50) is thereby used as both compression device and measuring device. The control is very simple, particularly when the apparatus according to Figs. 1 and 2 has besidethe control valves 4 and 5 also the valves [8, I9, 20, and 23 united into a fourway control valve.

I claim:

1. In a dry ice producing plant, a nozzle for the expansion of carbon dioxide to convert a portion thereof into snow; means to compress the snow; means to feed measured quantities of carbon dioxide to said nozzle means, comprising an expansible chamber formed by a cylinder and piston and conduit means connecting said cylinder to said nozzle, means for forcing carbon dioxide into said expansible chamber to move said piston in one direction therein; means connecting said piston to said snow compressing means so that the latter is operated when said piston is so moved, and. means to move said I piston in the opposite direction to force the carbon dioxide in said expansible chamber through said nozzle.

2. Apparatus for making dry ice, comprising a cylinder and plunger forming an expansible chamber to receive carbon dioxide snow, an expansion nozzle in one end of said chamber, a hydraulic press chamber comprising a cylinder and piston, connecting means joining said piston to said plunger, a compressor a condenser, means for conducting compressed carbon dioxide from said compressor to said condenser, means for conducting condensed carbon dioxide from said condenser to the side of said press cylinder opposite said connecting means, means for conducting carbon dioxide from said last-mentioned side'of said press cylinder to said nozzle, valves for controlling said conducting means, and means for moving said piston in the direction to withdraw said plunger from the nozzle end of said snow chamber and toJorce carbon dioxide from said press cylinder through said nozzle to convert a portion thereofinto snow.

3. In apparatus for producing dry ice, a pair of snow compressing chambers each comprising a cylinder and a plunger, a hydraulic press comprising a cylinder and a piston, means connecting said'piston to said plungers, expansion nozzles in said snow compressing cylinders, means for forcing carbon dioxide into said press cylinder alternately. on opposite sides of said piston, conduit means connecting the opposite sides ,of said press cylinder respectively with said nozzles, and valves for controlling said conduit means so that carbon dioxide is fed to said nozzle alternately in conformance with the direction of travel of said piston.

4. In apparatus for the production of dry ice, a pair of snow compression chambers each comprising a cylinder with a cover plate adapted to be opened to remove the block of compressed dry ice, and a plunger; a hydraulic press compressing a cylinder and a piston; means connecting said piston to each of said plungers; expansion nozzles in said snow compression chambers; a compressor; a condenser; conduit means connecting the pressure side of said compressor with said condenser; two conduits connecting said condenser with said press cylinder on opposite sides of the piston therein; valves controlling said two conduits; conduit means connecting the ends of said press cylinder on opposite sides of the piston therein with the nozzles in the respective snow compression chambers; valves controlling said last-mentioned conduit means; and means for conducting non-condensedgases from said snow compression chambers to the suction side of said.

compressor; the arrangement being such that carbon dioxide can be forced from said condenser into said press cylinder onone side of the piston therein, to move said piston in the direction to compress the snow contained'in one of said snow compression chambers, while a measured quantity of carbon dioxide on the other side of said piston is forced through the expansion nozzle in the other of said snow compression chambers to produce snow therein, and by re versal of said valves said piston can be moved in the opposite direction to reverse the compressing and snow'producing operations in said snow compression chambers.

5. In apparatus for the production of dry ice, a snow compression chamber comprising a cylinder and a p1unger,an expansion nozzle in said cylinder, a hydraulic press comprising a cylinder and a piston,.meansconnecting said piston to said plunger, a compressor, a condenser, means for conducting carbon dioxide from the'pressure side of said compressor to said condenser, a conduit connecting said condenser with the side of said press cylinder opposite said connecting means, a conduit connecting the last-mentioned side of said press cylinder with said nozzle, conduits connecting the side of said press cylinder on which said connecting means is located with both the pressure and the suction side oi. said compressor, conduit means for conveying uncondensed gases from said snow compression chamber to the suction side of said compressor, and

valves for controllingall of said conduits; the

arrangement being such that carbon dioxide can be forced from said condenser into said press cylinder on the side of said piston opposite said connecting means, to move said piston in the direction to compress carbon dioxide snow in said snow compression chamber, and by changing said I valves carbon dioxide can be forced by'said com-- pressor into the side of said press cylinder on which said connecting means is located, to move said piston in the opposite direction and to thereby force carbon dioxide from said press cylinder through said nozzle, to convert a portion thereof into snow. Y r j I I 6. The method of making dry ice, which comprises expelling through an expansion nozzle into an expansible chamber a measured quantity of liquid carbon dioxide, so as to convert a portion of it into snow; then compressing said snow into dry ice in said chamber by means of a carbon dioxide pressure liquid; then expelling a measured quantity of said "pressure a liquid force of said chamber against a previously formed quantity of carbon dioxide snow to compress the same into ice, thereafter contracting the expansible measuring chamber and thereby expelling the carbon dioxide therein through an expansion valve to convert a portion thereof into snow, and then repeating the process.

8. The method of making dry ice, which comprises forcing a quantity of liquid carbon dioxide into an expansible measuring chamber under a definite pressure while exerting the expanding force of said chamber against a previously formed quantity of carbon dioxide snow to compress the same into ice, and also against a second expansible measuring chamber containing a second quantity of, liquid carbon dioxide, thus exflblling said second quantity of carbon dioxide through an expansion nozzle to convert a portion thereof into snow; thereafter forcing a new quantity of liquid carbon dioxide into said second expansibie chamber under a definite pressure, while exerting the expanding force of said second chamber against the snow formed from the carbon dioxide previously expelled from said second chamber, and against said first .expansible chamber to expel the carbon dioxide therefrom through an expansion valve to convert a portion thereof into-snow, and then repeating the process.

9. The method described in claim 7, wherein the carbon dioxide which passes off as a gas as the remainder is converted into snow is compressed and condensed and returned to the cycle.

J OSEF KOBOLD. 

